The development of the Para rubber sector in Myanmar was slow for a long time from the early 1960s, mainly due to policy failures under the “Burmese Way to Socialism.” However, with the rubber boom around 2005–12, the sector started developing rapidly, as in other Asian tropical countries. The development of the sector is expected to be an important base for economic development in Myanmar through industrialization. This paper, based on information and data collected in Mon State in 2013 and 2014, clarifies the current status (with historical background) of various actors—including rubber estates (both private and government), smallholders, traders/processors, and tire factories—and investigates major problems they face. The rapid expansion of rubber plantation by smallholders in Mon State is particularly noteworthy, based on the study of two villages. It is found that the smallholders’ major source of investment is remittances from migrants working in the rubber sector in Southern Thailand. The migrants’ work experiences in Thailand, which expose them to technology and knowledge about supporting institutions, are expected to offer good potential for the future development of Myanmar’s rubber sector.